Previously available seed bed preparation implements exhibit a number of disadvantages and limitations. For example, some prior implements which included sub-soiler shanks cause the soil to "boil" up and outwardly to such a great extent that a large void is left in the soil behind the shanks. In order to fill the void it is necessary to move excessive amounts of dry top soil to the void where the dry soil is mixed with wet soil. This results in lowering of the moisture content of the soil in the seed bed, thereby hampering germination of seeds which are planted in the seed bed.
Also, some prior implements tend to move from side-to-side when they are towed across a field. This is very undesirable because the seed beds are not straight, and in some areas the seed beds from one pass of the implement across the field are too close to the seed beds prepared with the next pass across the field.
The prior implements do not provide any means for conveniently and effectively aligning a planter with the prepared seed beds. This requires the operator of the planter to be particularly careful so that the seeds are planted in the proper place.
Prior implements also do not work well in heavier clay soils. This drawback can limit the utility of such implements.
There has not heretofore been provided a minimum tillage implement having the advantages exhibited by the implement of the present invention.